Treatment is usually more successful in children than in adults. Occasionally in children and more commonly in adults, systemic therapies are used to keep the dermatitis under control. Oral antihistamines and immunosuppressive agents are not uncommonly required. A subset of patients respond to ultraviolet phototherapy, but most are not able to tolerate the warmth and sweating that is induced by the phototherapy unit. Oral immunosuppressants are used and include cyclosporine, azathioprine, and mycophenolate mofetil. These medications have severe potential side effects and should be administered only by experienced clinicians. Routine laboratory testing is required with all of these medications.